NoteTime zones and location of the server do not matter for NTP; it synchronizes via UTC.

By default the Gentoo servers are listed and enabled. A list of available servers can be found on ntp.org. A home or company server here can be used, if ntpd is running and the machine is allowed access.

On systems where a network connection is not always available at boot (laptops, etc.), it might help to add the following lines to server configuration:

FILE/etc/ntp.conf

server 127.127.1.0
fudge 127.127.1.0 stratum 10

This sets localhost as a server with low priority, so that the daemon starts properly even without a network connection and switches to using network servers when a connection is established.

Permissions

Permission are used to control who is allowed to synchronize or change permissions.

Access to NTP service allowed only from localhost. noquery can be added to help prevent the server from being abused to conduct DDOS attacks:

# To allow machines within the local network to synchronize
# their clocks with this server, but ensure they are
# not allowed to configure the server or used as peers
# to synchronize against, uncomment this line.
#
restrict 192.168.0.0 mask 255.255.255.0 nomodify nopeer notrap

Denying access to NTP's monlist functionality, used for querying traffic stats but also exploited in a denial-of-service attack.

FILE/etc/ntp.conf

disable monitor

Usage

Basic tools and common usage.

Client

ntp-client

To start the ntp-client:

root #rc-service ntp-client start

To view the status of the client:

root #rc-service ntp-client status

To have the client start at boot:

root #rc-update add ntp-client default

ntpdate

This used to be the client, but its functionality is now moved into ntpd and ntp-client itself. It is purely to set the local time when started and then exits (not a service):

root #ntpdate pool.ntp.org

Server

The server is both a client, and server. If the setup can not access net early in init, use server only instead.

ntpd service

If ntpd is run as a service, the time will automatically synchronize as long as the difference between the local time and the time on the server is less than 1000s (~17 mins). So it is pretty common to adjust the time initially to whatever the server time is as a trusted source:

root #ntpd -g -c /etc/ntp.conf

NoteIf ntpd is already running, it will not start a second time.

Add ntpd to the default runlevel to have the time synchronized automatically. There is no need to run a client when the service is running. In this case verify that ntp-client or ntpdate are not in any runlevels.

root #rc-update

When it is confirmed the configuration is clear from ntp-client or ntpdate, add the ntpd service: